Memory devices developed based on semiconductor techniques, such as dynamic random access memory (DRAM), static random access memory (SRAM), and non-volatile memory, have played a major part in today's semiconductor industry. These memories have been broadly applied to personal computers, mobile phones, and networks and have become one of the most indispensable electronic products in our daily life.
The demand for memories having low power consumption, low cost, high access speed, small volume, and high capacity has been increasing drastically along with the widespread of consumable electronic products and system products. Recording data by changing the resistance of a variable resistance layer is a promising alternative to storing charge or magnetization.
Resistive random access memory (RRAM) has recently gained tremendous popularity due to its high endurance switching while consuming lower voltage than Flash (<5V). RRAM also has the ability to scale further than NAND flash at lower cost, due to its relatively simple structure, and decoupling from front-end process. However, NAND technology has been moving to a bit-cost-scalable (BICS) methodology, which allows a 3D multilayer structure to be built with minimal cost. In order for RRAM to complete with this form of NAND flash on cost, it also must be able to be built in a similar fashion. Since RRAM will not require the extra chip area for charge pumping for the typically high (about 10˜20 V) voltages required for NAND flash programming, a BICS-style RRAM will ultimately prevail for high-density memory.